Axle shims which allow an 7mm to 8mm conversion. These metal shims allow for 7mm axles to take 8mm bearings and other products - Each one is a tiny metal barrel or sleeve which fits around the axle and makes it thicker at that point. So you can use 8mm bearings on 7mm axles if you have this shim. The last American to manufacture these has closed shop so there is a limited supply. Order 8 for a full set for one pair of roller skates.